Pallets have been constructed from a number of materials. The most common pallet in use today is manufactured from relatively cheap wood products. Typically the pallet will have two or more stringers and a plurality of deck boards extending transversely across the stringers. One or more deck boards may be attached to the lower surface of the stringers to provide suitable rigidity of the stringers.
Other materials have been utilized for the production of pallets. One example of a pallet is that shown in U.S. Pat. No. 4,145,976 which issued Mar. 27, 1979 (Svirklys), assigned to Extrados Company Limited. The pallet shown in that patent is of a knock-down type construction with a plurality of releasably interlocking parts. In order to provide improved strength, separate end caps are provided in each end of each stringer element with the end caps acting as part of the fastening arrangement of the end deck forming member. In this patent the deck members have relatively uniform cross-section at any point along their length and may be made from an extrusion procession.
Materials used for manufacturing pallets must be strong and rugged enough to serve the purpose of supporting the load to be carried on the pallet while also being relatively inexpensive. In order to have strong structures which are lightweight, it is desirable to have box structures rather than using solid members. However, in order to prevent a box structure from filling with liquids and solids such as mud, sand, gravel or other substances upon which the pallet may be placed or where the pallet may be stored, the boxed structures should be closed. While a boxed structure may be closed by the addition of caps, this then necessitates the need for constructing a separate member and affixing that member to the box structure.
It is therefore desired to provide a pallet made of thin walled hollow members which are closed. The members may be made from plastic. In particular, pallets of the type discussed are a particularly good use for recycled plastic materials. The pallet may be made from entirely recycled material or from mixes of virgin resin and recycled material. One of the advantages of such pallets is that the pallets, when damaged or broken, as will inevitably occur, may themselves be recycled to create new pallets. Thus, there are significant economies by the use of recycled material and by recycling damaged pallets or parts thereof.
Thin walled hollow members which are integrally closed may be manufactured using known blow moulding processes. Alternatively the use of continuous extrusion equipment similar to that used to produce corrugated or flexible piping may also be used to make closed structures for use in pallets in accordance with this invention.